Slippage compensator for sound units



April 14, 1936. E. lsolzczKlNc;v

. SLIPPAGE COMPENSATYOR FOR SOUND UNITS E. BOECKING SLIPPGE COMPENSATOR FOR SOUND UNITS April 14, 1936.V

Filed Feb. 19, 1954 2 Sheets-Sheet 2 INVENTOR y [wa/a oec/f/)Zg lBY' hun@ bw ATTORNEYS- Patented Apr.`1'4, 193e PATENT OFFICE smrA'GE coMPENsA'ron' ron soUND Um'rs Ewald Boecking, Brooklyn, N. Y., assignor tovIn` tcrnatonal Projector Corporation, New York,

N. Y., a corporation of Delaware Application February 19, 1934, Serial No. 711,999

2 Claims.

This invention relates to a simple and efficient device to be used for the purpose of regulating the directional and tensional condition of a film passing between driving elements such as spr'ock- 5 ets and has particular reference to such a device when employed Yto regulate the tension and movement of a nlm passing through a motion picture projector which has a sound unit therein.

A main feature of the invention is to provide a simple, compact, and eflicientmechanism whereby the film as it passes froml one sprocket to another is regulated as to its tension and direcvtion of movement so that irregular and jerky movements of the film are avoided, whereby in crossing a sound light beam in the unit, for instance, irregularities in the sound will not be produced.`

A further feature is to provide a simple mechanism, economical to manufacture which has the broader application to the regulation of a film passing between sprockets, such as in a camera, a lm printing machine or other similar device, where it is vital that the direction and position of the lm, at least along part of its trav el, shall remain and be maintained in a predetermined manner.

A still further feature is to provide a simple mechanism which will automatically keep the film in proper position and under constant tension irrespective of the tendency of the film to alterits position due to irregularities in the mechanical assemblage of the film driving sprockets or mechanisms as well as to differences in the spacing of the film sprocket holes.

Further and more specic features, objects,

and advantages will more clearly appear from a` consideration of the specication when taken in connection with the accompanying drawings which form part of the specification and which illustrate present preferred forms of the invention.

A general but brief contemplation of the invention discloses a pairof elements such as sprockets with which a iil'm is engaged and by'which it is moved-therebetween. The field traversed by the lm between these'two driving elements is important only in that it is vital to regulate the tension and direction of movement of the lm in it. This field may be in a projector, acamera, a printing machine, or other device. In the form shown in the drawings a motion picture projector is .employed'with a sound unit and g it is the motion of the nlm between the two sprockets of the sound unit which is important in the selected instance. It is important because in this particular eld the nlm crosses the sound light beam and any major variations of the position of the film in crossing the beam or any non-uniformity or jerk in its movement across the' beam will detrimentally affect the sound produced. The drivingsprockets are generally connected by gearing and in the mechanical assemblage which connects'them there 'is likely to be a certain amount of looseness or backlash which might cause irregularity in fllm movement. There is also the factor that the film sprocket holes may slightly differ in size and in'space relation which would cause the film to jerk or slip on thesprockets and cause irregular movement.

To overcome these factors causing irregular movement, which cannot be. easily avoided in commercial production, a nlm-engaging plate is disposed to engage the'film at a determined point between the two driving or moving elements. This point will be different 'depending upon what .sort of machine is employing the invention, but,`

' in the form shown the point is that point where the nlm crosses the sound beam in Athe sound unit of a modern motion picture and sound projector. This plate is resiliently mounted so that it exerts a sort of double regulating action on theA iilmto maintain its tension and motion across the beam in a substantially constant manner.

yThis regulating element or plate exerts a pull on the portion of the lm coming from the one sprocket to the plate and also a similar pull on that portion of the film which extends from the plate to the second sprocket. As a consequence' of this steadyv regulating tendency, the film is maintained in its proper position in its movement and jerky movement thereof is avoided, especially as it travels from one sprocket to the other. This regulation as it crosses the beam in the specific form shown, is important for the reasons mentioned above. This same sort of regulationA between sprockets is equally vital and applicable with this invention as applied to many other devices and machines through which a lm may be passed for other purposes than the projection of sound motion pictures as indicated above.

As shown in the drawings the present preferred forms of the invention are set forth as follows:-

`Fig. 1 is a side view of part of the sound mechanism of the projector;

Fig. 2 is a vertical cross section thereof taken on the line 2^2 of Fig. 1;

Fig. 3 is an enlarged expanded semi-diagrammatic view' of the manner in-which the nlm is engaged by the pair of sprockets and the intermediate regulating plate;

Fig. 4 is a partial inverted elevational view of the engagement of the film by a tooth on the first orl hold-back sprocket;

Fig. 5 is a partial side elevation of the engagement of the film by the other or driving sprocket; and,

Fig. 6 is a view. similar to Fig. 3, and shows a modified form of the invention. l

As shown in the drawings, vthere is provided a lamp I0, a. lens combination unit Il, and a photo-electric cell I2. and the lens combination unit II there is disposed an oscillatable film engaging plate or frame comprising spaced bars I3 and I4 connected at one end by a cross bar I5, supported on a shaft I6 journalled in a. pedestal I1 forming part of the main frame of the projector. AThe end of the shaft I6 projects through and beyond thepedesta] I'I, and carries on its outer end a collar I8. A spring I9 is coiled around the end of the shaft I6 and is disposed between the collar Il and the adjacent face of the pedestal II. One end of the spring I9 is fastened to the pedestal and the other end to the collar I8. The tendency of the spring I9 is to turn the film-engaging .plate or frame in the direction as indicated by the arrows in Figs. 1 and 3.

The spaced bars I3 and I4 forming the filmengaging frame or plate are, on their respective ends, provided with curved spring plates or guide members 20 and 2l as shown which extend outwardly in a curved manner from the respective bars and provide curved guides for the film and lead the iilm toward and away'from the plate or frame as shown in Figs. 1 and 3. The film 22, see Fig. 1, passes downwardly between a roller and the hold-back sprocket 24, thence over the guide spring plate 20, down'between the bars I3 and I4, and then around and over the guide spring plate 2|. Thence it passes between the drive sprocket 25 and a presser plate 26, whence' it continues through the apparatus in any usual .and desired manner. The hold-back sprocket 24 actually engages the film by means of the teeth thereon and positively assists in moving the film through the machine whereby it functions' more than as a vmere idler roller would.

considering Fig. 3, 1t will be seen that the' action of the regulating and film-engaging element or plate disposed between the sprockets 24 and 25 is to pull the two portions of the film in opposite directions. The upper end of the plate pulls the film in a direction to the right and the lower portion of the plate pulls the film in a direction toward the left. It will thus be seen that this tendency of the regulating and tensioning plate is to keep the film so disposed on the sprockets 24 and 25 that the teeth of the sprockets always engage the film sprocket holes firmly and snugly so that any tendency of the film to slip due to back lash in the mechanism or non-uniformity of the holes is instantly corrected and compensated for. As will be seen in 24 is always bearing against the back of the hole due to the pulling action of the regulating plate,

Between the cell unit I2 tending from the frame I'I. Abar 29 pivoted to .the end of the frame 21 passes through a boss 30 and has a threaded lower end with which a screw nut 3| engages so thatI the angular position of the frame 21 and consequently the position of the presser plate 26 with respect to the sprocket 25 can be adjusted. 'I'his provision will permit the presserl plate to be adjusted at assembly or afterwards so that the departure of the film from the sprocket 25 can be varied dependent upon the particular film used, the sprocket hole spacing, and the back lash conditions found with the particular assembly employed. This will enable the operator to locate the film asrshown in Fig. 3 so that at least one tooth on the drive sprocket 25 will be engaged as shown with the film. Which tooth is in engagement to pull depends upon the various variable factors previously mentioned. He likewise can engage the film holes properly with respect to the teeth on the hold-back sprocket 24 in the same manner.

As lshown in- Fig. 6, the film after leaving the driving sprocket 25 may pass beneath a curved spring 33 and then to another sprocket 32. This spring is adjustable on a slide pedestal or element 34 mounted adjustably on a screw 36 turnable in a support35. Therefore the direction with which the film may leave the sprocket 25 can be adjusted by moving the position of the spring 33as shown. This is a modification of the means whereby the point of departure of the film from the drive sprocket can be adjusted.

The regulating frame formed by the bars I3 and I4 may be considered as an oscillatable support, apertured, and having a leading edge on the bar I3 and a trailing edge on the bar I4. This frame or element tensions the film received between the bars and pulls on it in opposite directions for the purposes mentioned; It is adjusted by reason of the spring I9 to maintain the film movement in a substantially constant direction as the film passes across the light beam. It is obvious that this tensioning and direction regulation may be with respect to other elements than the light beam here shown as may be required in other machines in which the invention may be employed for similar film regulating purposes.

It will therefore be seen that this invention provides a simple and eiiicient means whereby the lm asit passes by a given portion of its path,

tional position with respect to this portion of its path and that any slight tendencies of the film to jerk or slip are instantly taken up by the resiliently mounted oscillatable plate or frame. After the film has been adjusted to the sprockets with the teeth engaging as shown in Figs. 4 and 5, then the entire action thereafter is taken care of by the action of the regulating frame to pull the film in opposite directions at all times and instantly to take up any jerk or slip that may tend to occur due to the factors previously mentioned. After the nlm has been disposed on the parts with proper respect for the hole arrangement and spacing, then the presser plate 26 or its modification can be adjusted to give the desired angle oi' departure to the film.

It is clearly apparent that this same device can be used in other machines than the one shown. In any machine where a film passes through it may be desirable to positively engage a film on opposite sides of a given point in its travel between two sprockets or'similar feeding means to positively move it and then provide a 'lov 9,031,459 definite regulating such as the regulating piste or frame shown for determining its directional and tensional condition in this part of its path between the sprockets.

While the invention has been described in detail and with respect to present preferred forms thereof, it is not to be limited to such details and forms since many changes and modifications may be made in the invention without departing from the spirit and scope of the invention in its broadest aspects. Hence it is desired to cover any and all forms and modifications of the invention which may come within the language or scopeof any one or more of the appended claims.

I claim:

1. In apparatus of the character described for recording, printing or reproducing sound, wherein a iilm is passed through a beam of light,` a sprocket on one side of said beam for assisting in controlling the rate of feed of said illmpast the beam, a sprocket on the opposite side of said beam for drawing the nlm forward at a controlled rate, and means constructed and arranged to frictionally and resiliently engage said film adjacent the opposite edges of the beam for pulling the portion of the film in the beam forward from the first sprocket and rearward from. the second sprocket 'and for guiding said portion of the nlm l into a plane substantially perpendicular to the beam, said nlm portion being completely free from engagement, between the eifective edges of the beam.

2. In apparatus of the character described for recording, printing or reproducing sound, wherein a film 'is passed through a beam of light, a sprocket on one .side ofl said beam for assisting 1 in controlling the rate of feed of said film past the beam, a sprocket on the opposite side of said beam for drawing the iilm forward at a controlled rate, and. means constructed and arranged to irlctionally and resiliently engage said film adjacent the opposite edges of the beam for pulling the portion of the film in the beam forward from the first sprocket and rearward from the second sprocket and for guiding said portion of the film into a plane substantially perpendicular to the beam. Said 111m portion being completely free from engagement, between the eifective edges of the beam, and said means comprising a pair of diametrically opposed curvilinear elements adapted to engage opposite sides of the film and being mounted on a pivot, and a resilient device adapted to rotate said elements about the pivot. Y EWALD BOECKING. 

